package com.blog.sys.common.utils.file;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import javax.servlet.http.HttpServletRequest;


/**
 *
 * @ProjectName:    blog
 * @Package:        com.yk.blog.common.utils.file
 * @ClassName:      FileUtils
 * @Description:    文件处理工具类
 * @Author:         yanakai@126.com
 * @CreateDate:     2019/9/26 23:38
 * @UpdateUser:     yanakai@126.com
 * @UpdateDate:     2019/9/26 23:38
 * @UpdateRemark:   更新内容
 * @Version:        1.0
 */

public class FileUtils{
    public static String FILENAME_PATTERN = "[a-zA-Z0-9_\\-\\|\\.\\u4e00-\\u9fa5]+";

    /**
     * 输出指定文件的byte数组
     * 
     * @param filePath 文件路径
     * @param os 输出流
     * @return
     */
    public static void writeBytes(String filePath, OutputStream os) throws IOException{
        FileInputStream fis = null;
        try{
            File file = new File(filePath);
            if (!file.exists()){
                throw new FileNotFoundException(filePath);
            }
            fis = new FileInputStream(file);
            byte[] b = new byte[1024];
            int length;
            while ((length = fis.read(b)) > 0)
            {
                os.write(b, 0, length);
            }
        }catch (IOException e){
            throw e;
        }finally{
            if (os != null){
                try{
                    os.close();
                }catch (IOException e1){
                    e1.printStackTrace();
                }
            }if (fis != null){
                try {
                    fis.close();
                }catch (IOException e1){
                    e1.printStackTrace();
                }
            }
        }
    }

    /**
     * 删除文件
     * 
     * @param filePath 文件
     * @return
     */
    public static boolean deleteFile(String filePath){
        boolean flag = false;
        File file = new File(filePath);
        // 路径为文件且不为空则进行删除
        if (file.isFile() && file.exists()){
            file.delete();
            flag = true;
        }
        return flag;
    }

    /**
     * 文件名称验证
     * 
     * @param filename 文件名称
     * @return true 正常 false 非法
     */
    public static boolean isValidFilename(String filename){
        return filename.matches(FILENAME_PATTERN);
    }

    /**
     * 下载文件名重新编码
     * 
     * @param request 请求对象
     * @param fileName 文件名
     * @return 编码后的文件名
     */
    public static String setFileDownloadHeader(HttpServletRequest request, String fileName)
            throws UnsupportedEncodingException {
        final String agent = request.getHeader("USER-AGENT");
        String filename = fileName;
        if (agent.contains("MSIE")){
            // IE浏览器
            filename = URLEncoder.encode(filename, "utf-8");
            filename = filename.replace("+", " ");
        }else if (agent.contains("Firefox")){
            // 火狐浏览器
            filename = new String(fileName.getBytes(), "ISO8859-1");
        }else if (agent.contains("Chrome")){
            // google浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }else{
            // 其它浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        return filename;
    }
}
